Expandable and angularly adjustable intervertebral cages with articulating joint

ABSTRACT

The embodiments provide various interbody fusion spacers, or cages, for insertion between adjacent vertebrae. The cages may contain an articulating joint to allow expansion and angular adjustment, and enable upper and lower plate components to move relative to one another. The cages may have a first, insertion configuration characterized by a reduced size at each of their insertion ends to facilitate insertion through a narrow access passage and into the intervertebral space. In their second, expanded configuration, the cages are able to maintain the proper disc height and stabilize the spine by restoring sagittal balance and alignment. The intervertebral cages are able to adjust the angle of lordosis, and can accommodate larger lodortic angles in their second, expanded configuration. Further, these cages may promote fusion to further enhance spine stability by immobilizing the adjacent vertebral bodies.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims benefit of U.S. Provisional Application No.62/355,619, filed Jun. 28, 2016, the entirety of which is hereinincorporated by reference.

FIELD

The present disclosure relates to orthopedic implantable devices, andmore particularly implantable devices for stabilizing the spine. Evenmore particularly, the present disclosure is directed to expandable,angularly adjustable intervertebral cages comprising articulatingmechanisms that allow expansion from a first, insertion configurationhaving a reduced size to a second, implanted configuration having anexpanded size. The intervertebral cages are configured to adjust andadapt to lodortic angles, particularly larger lodortic angles, whilerestoring sagittal balance and alignment of the spine.

BACKGROUND

The use of fusion-promoting interbody implantable devices, oftenreferred to as cages or spacers, is well known as the standard of carefor the treatment of certain spinal disorders or diseases. For example,in one type of spinal disorder, the intervertebral disc has deterioratedor become damaged due to acute injury or trauma, disc disease or simplythe natural aging process. A healthy intervertebral disc serves tostabilize the spine and distribute forces between vertebrae, as well ascushion the vertebral bodies. A weakened or damaged disc thereforeresults in an imbalance of forces and instability of the spine,resulting in discomfort and pain. A typical treatment may involvesurgical removal of a portion or all of the diseased or damagedintervertebral disc in a process known as a partial or total discectomy,respectively. The discectomy is often followed by the insertion of acage or spacer to stabilize this weakened or damaged spinal region. Thiscage or spacer serves to reduce or inhibit mobility in the treated area,in order to avoid further progression of the damage and/or to reduce oralleviate pain caused by the damage or injury. Moreover, these type ofcages or spacers serve as mechanical or structural scaffolds to restoreand maintain normal disc height, and in some cases, can also promotebony fusion between the adjacent vertebrae.

However, one of the current challenges of these types of procedures isthe very limited working space afforded the surgeon to manipulate andinsert the cage into the intervertebral area to be treated. Access tothe intervertebral space requires navigation around retracted adjacentvessels and tissues such as the aorta, vena cava, dura and nerve roots,leaving a very narrow pathway for access. The opening to the intradiscalspace itself is also relatively small. Hence, there are physicallimitations on the actual size of the cage that can be inserted withoutsignificantly disrupting the surrounding tissue or the vertebral bodiesthemselves.

Further complicating the issue is the fact that the vertebral bodies arenot positioned parallel to one another in a normal spine. There is anatural curvature to the spine due to the angular relationship of thevertebral bodies relative to one another. The ideal cage must be able toaccommodate this angular relationship of the vertebral bodies, or elsethe cage will not sit properly when inside the intervertebral space. Animproperly fitted cage would either become dislodged or migrate out ofposition, and lose effectiveness over time, or worse, further damage thealready weakened area.

Thus, it is desirable to provide intervertebral cages or spacers thatnot only have the mechanical strength or structural integrity to restoredisc height or vertebral alignment to the spinal segment to be treated,but also be configured to easily pass through the narrow access pathwayinto the intervertebral space, and then accommodate the angularconstraints of this space, particularly for larger lodortic angles.

BRIEF SUMMARY

The present disclosure describes spinal implantable devices that addressthe aforementioned challenges and meet the desired objectives. Thesespinal implantable devices, or more specifically intervertebral cages orspacers, are configured to be expandable as well as angularlyadjustable. The cages may comprise upper and lower plate componentsconnected by articulating expansion or adjustment mechanisms that allowthe cage to change size and angle as needed, with little effort. In someembodiments, the cages may have a first, insertion configurationcharacterized by a reduced size at their insertion ends to facilitateinsertion through a narrow access passage and into the intervertebralspace. The cages may be inserted in a first, reduced size and thenexpanded to a second, expanded size once implanted. In their secondconfiguration, the cages are able to maintain the proper disc height andstabilize the spine by restoring sagittal balance and alignment. It iscontemplated that, in some embodiments, the intervertebral cages mayalso be designed to allow the cages to expand in a freely selectable (orstepless) manner to reach its second, expanded configuration. Theintervertebral cages are configured to be able to adjust the angle oflordosis, and can accommodate larger lodortic angles in their second,expanded configuration. Further, these cages may promote fusion tofurther enhance spine stability by immobilizing the adjacent vertebralbodies.

Additionally, the implantable devices may be manufactured usingselective laser melting (SLM) techniques, a form of additivemanufacturing. The devices may also be manufactured by other comparabletechniques, such as for example, 3D printing, electron beam melting(EBM), layer deposition, and rapid manufacturing. With these productiontechniques, it is possible to create an all-in-one, multi-componentdevice which may have interconnected and movable parts without furtherneed for external fixation or attachment elements to keep the componentstogether. Accordingly, the intervertebral cages of the presentdisclosure are formed of multiple, interconnected parts that do notrequire additional external fixation elements to keep together.

Even more relevant, devices manufactured in this manner would not haveconnection seams whereas devices traditionally manufactured would havejoined seams to connect one component to another. These connection seamscan often represent weakened areas of the implantable device,particularly when the bonds of these seams wear or break over time withrepeated use or under stress. By manufacturing the disclosed implantabledevices using additive manufacturing, one of the advantages is thatconnection seams are avoided entirely and therefore the problem isavoided.

Another advantage of the present devices is that, by manufacturing thesedevices using an additive manufacturing process, all of the componentsof the device (that is, both the intervertebral cage and the pins forexpanding and blocking) remain a complete construct during both theinsertion process as well as the expansion process. That is, multiplecomponents are provided together as a collective single unit so that thecollective single unit is inserted into the patient, actuated to allowexpansion, and then allowed to remain as a collective single unit insitu. In contrast to other cages requiring external expansion screws orwedges for expansion, in the present embodiments the expansion andblocking components do not need to be inserted into the cage, norremoved from the cage, at any stage during the process. This is becausethese components are manufactured to be captured internal to the cages,and while freely movable within the cage, are already contained withinthe cage so that no additional insertion or removal is necessary.

In some embodiments, the cages can be made with an engineered cellularstructure that includes a network of pores, microstructures andnanostructures to facilitate osteosynthesis. For example, the engineeredcellular structure can comprise an interconnected network of pores andother micro and nano sized structures that take on a mesh-likeappearance. These engineered cellular structures can be provided byetching or blasting to change the surface of the device on the nanolevel. One type of etching process may utilize, for example, HF acidtreatment. In addition, these cages can also include internal imagingmarkers that allow the user to properly align the device and generallyfacilitate insertion through visualization during navigation. Theimaging marker shows up as a solid body amongst the mesh under x-ray,fluoroscopy or CT scan, for example.

Another benefit provided by the implantable devices of the presentdisclosure is that they are able to be specifically customized to thepatient's needs. Customization of the implantable devices is relevant toproviding a preferred modulus matching between the implant device andthe various qualities and types of bone being treated, such as forexample, cortical versus cancellous, apophyseal versus central, andsclerotic versus osteopenic bone, each of which has its own differentcompression to structural failure data. Likewise, similar data can alsobe generated for various implant designs, such as for example, porousversus solid, trabecular versus non-trabecular, etc. Such data may becadaveric, or computer finite element generated. Clinical correlationwith, for example, DEXA data can also allow implantable devices to bedesigned specifically for use with sclerotic, normal, or osteopenicbone. Thus, the ability to provide customized implantable devices suchas the ones provided herein allow the matching of the Elastic Modulus ofComplex Structures (EMOCS), which enable implantable devices to beengineered to minimize mismatch, mitigate subsidence and optimizehealing, thereby providing better clinical outcomes.

In one exemplary embodiment, an expandable spinal implant is provided.The expandable spinal implant may comprise an upper plate componentconfigured for placement against an endplate of a first vertebral body,and a lower plate component configured for placement against an endplateof a second, adjacent vertebral body, the upper and lower platecomponents being connected at an articulating joint, and a blocking pincomprising a shaft and an enlarged head portion, the blocking pin beingconfigured to effect angular adjustment of the expandable spinal implantas the pin is advanced toward an anterior end of the implant. Thearticulating joint may be configured to allow pivoting movement of theupper and lower plate components relative to one another.

The spinal implant including the blocking pin may be manufactured by anadditive production technique, with the blocking pin being manufacturedas a separate component to reside inside but still be moveable withinthe cage. In some embodiments, the expandable spinal implant may be aPLIF (posterior lumbar interbody fusion) cage. The expandable spinalimplant may have a first configuration wherein the plate components areangled toward one another at an anterior portion, then parallel to oneanother in an intermediate configuration, and a second configurationwherein the plate components are locked together and are angled relativeto one another at a posterior portion. In the second configuration, theimplant adjusts the angle of lordosis, and restores the sagittal balanceand alignment of the spine.

Although the following discussion focuses on spinal implants, it will beappreciated that many of the principles may equally be applied to otherstructural body parts requiring bone repair or bone fusion within ahuman or animal body, including other joints such as knee, shoulder,ankle or finger joints.

It is to be understood that both the foregoing general description andthe following detailed description are exemplary and explanatory onlyand are not restrictive of the disclosure. Additional features of thedisclosure will be set forth in part in the description which follows ormay be learned by practice of the disclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated in and constitute apart of this specification, illustrate several embodiments of thedisclosure and together with the description, serve to explain theprinciples of the disclosure.

FIG. 1 illustrates a perspective view of an exemplary embodiment of anintervertebral cage in accordance with the present disclosure.

FIG. 2A illustrates an anterior view of the intervertebral cage of FIG.

FIG. 2B illustrates a lateral view of the intervertebral cage of FIG. 1.

FIG. 2C illustrates a posterior view of the intervertebral cage of FIG.

FIG. 2D illustrates a cranial-caudal view of the intervertebral cage ofFIG. 1 .

FIG. 2E illustrates an isometric view of the intervertebral cage of FIG.1 .

FIG. 3 illustrates an exploded view of the intervertebral cage of FIG. 1and associated blocking pin.

FIG. 4A illustrates a side view of the intervertebral cage of FIG. 1 andassociated blocking pin in its manufactured position.

FIG. 4B illustrates a cross-sectional view of the intervertebral cageand blocking pin of FIG. 4A.

FIGS. 5A-5C illustrate various views of the upper plate component of theintervertebral cage of FIG. 1 , in which FIG. 5A illustrates a sideview, FIG. 5B illustrates a partial cutaway view, and FIG. 5Cillustrates a perspective view.

FIGS. 6A-6C illustrate various views of the lower plate component of theintervertebral cage of FIG. 1 , in which FIG. 6A illustrates a sideview, FIG. 6B illustrates a perspective view, and FIG. 6C illustrates anenlarged posterior view.

FIGS. 7A and 7B illustrate various views of the blocking pin of FIG. 3 ,in which FIG. 7A illustrates a top-down view and FIG. 7B illustrates aperspective view.

FIGS. 8A-8J illustrate a method of expanding the intervertebral cage ofFIG. 1 , in which FIGS. 8A, 8C, 8E, 8G, and 8I illustrate lateral viewsof the cage over the course of expansion, while FIGS. 8B, 8D, 8F, 8H,and 8J illustrate cross-sectional views of the cage over the course ofexpansion.

DETAILED DESCRIPTION

The present disclosure provides various spinal implant devices, such asinterbody fusion spacers, or cages, for insertion between adjacentvertebrae. The devices can be configured for use in either the cervicalor lumbar region of the spine. In some embodiments, these devices areconfigured as PLIF cages, or posterior lumbar interbody fusion cages.These cages can restore and maintain intervertebral height of the spinalsegment to be treated, and stabilize the spine by restoring sagittalbalance and alignment. In some embodiments, the cages may contain anarticulating joint to allow expansion and angular adjustment. Thisarticulating joint allows upper and lower plate components to moverelative to one another. The cages may have a first, insertionconfiguration characterized by a reduced size at each of their insertionends to facilitate insertion through a narrow access passage and intothe intervertebral space. The cages may be inserted in a first, reducedsize and then expanded to a second, expanded size once implanted. Intheir second configuration, the cages are able to maintain the properdisc height and stabilize the spine by restoring sagittal balance andalignment. It is contemplated that, in some embodiments, theintervertebral cages may also be designed to allow the cages to expandin a freely selectable (or stepless) manner to reach its second,expanded configuration. The intervertebral cages are configured to beable to adjust the angle of lordosis, and can accommodate largerlodortic angles in their second, expanded configuration. Further, thesecages may promote fusion to further enhance spine stability byimmobilizing the adjacent vertebral bodies.

Additionally, the implantable devices may be manufactured usingselective laser melting (SLM) techniques, a form of additivemanufacturing. The devices may also be manufactured by other comparabletechniques, such as for example, 3D printing, electron beam melting(EBM), layer deposition, and rapid manufacturing. With these productiontechniques, it is possible to create an all-in-one, multi-componentdevice which may have interconnected and movable parts without furtherneed for external fixation or attachment elements to keep the componentstogether. Accordingly, the intervertebral cages of the presentdisclosure are formed of multiple, interconnected parts that do notrequire additional external fixation elements to keep together.

Even more relevant, devices manufactured in this manner would not haveconnection seams whereas devices traditionally manufactured would havejoined seams to connect one component to another. These connection seamscan often represent weakened areas of the implantable device,particularly when the bonds of these seams wear or break over time withrepeated use or under stress. By manufacturing the disclosed implantabledevices using additive manufacturing, connection seams are avoidedentirely and therefore the problem is avoided.

In some embodiments, the cages can be made with an engineered cellularstructure that includes a network of pores, microstructures andnanostructures to facilitate osteosynthesis. For example, the engineeredcellular can comprise an interconnected network of pores and other microand nano sized structures that take on a mesh-like appearance. Theseengineered cellular structures can be provided by etching or blasting tochange the surface of the device on the nano level. One type of etchingprocess may utilize, for example, HF acid treatment. In addition, thesecages can also include internal imaging markers that allow the user toproperly align the cage and generally facilitate insertion throughvisualization during navigation. The imaging marker shows up as a solidbody amongst the mesh under x-ray, fluoroscopy or CT scan, for example.

Another benefit provided by the implantable devices of the presentdisclosure is that they are able to be specifically customized to thepatient's needs. Customization of the implantable devices is relevant toproviding a preferred modulus matching between the implant device andthe various qualities and types of bone being treated, such as forexample, cortical versus cancellous, apophyseal versus central, andsclerotic versus osteopenic bone, each of which has its own differentcompression to structural failure data. Likewise, similar data can alsobe generated for various implant designs, such as for example, porousversus solid, trabecular versus non-trabecular, etc. Such data may becadaveric, or computer finite element generated. Clinical correlationwith, for example, DEXA data can also allow implantable devices to bedesigned specifically for use with sclerotic, normal, or osteopenicbone. Thus, the ability to provide customized implantable devices suchas the ones provided herein allow the matching of the Elastic Modulus ofComplex Structures (EMOCS), which enable implantable devices to beengineered to minimize mismatch, mitigate subsidence and optimizehealing, thereby providing better clinical outcomes.

Turning now to the drawings, FIG. 1 shows an exemplary embodiment of anexpandable and angularly adjustable intervertebral cage 10 of thepresent disclosure. The cage 10 may comprise a pair of articulatingshells or plate components 20, 40 configured for placement againstendplates of a pair of adjacent vertebral bodies. In one embodiment, thearticulating plate components may include a flat surface for placementagainst the endplates.

As illustrated in greater detail in FIGS. 2A to 2E, in which FIG. 2Ashows the anterior view of the cage 10, FIG. 2B shows the side orlateral view of the cage 10, FIG. 2C shows the posterior view of thecage 10, FIG. 2D shows the cranial-caudal view of the cage 10, and FIG.2E shows the isometric view of the cage 10, the cage 10 may comprise anupper plate component 20 and a bottom plate component 40 configured toarticulate relative to one another at an articulating joint. In thepresent embodiment, movement of the plate components 20, 40 can berealized by an articulating joint mechanism residing between thesecomponents 20, 40, allowing the internal surfaces of the components 20,40 to slide relative to one another. In other words, the bottom platecomponent 40 serves as the base, while the upper plate component 20rocks back and forth in a see-saw like motion relative to the base 40.

FIG. 3 illustrates an exploded view of the assembly of theintervertebral cage 10 and blocking pin 60 of the present embodiment.The base or lower plate component 40 may comprise an internal housing 42having a slot or cavity 48 for receiving the blocking pin 60. This slotor cavity 48 can communicate with a port or channel 44 at the rear ofthe housing 42, at the second trailing end 14 of the cage 10, to receiveand move the pin 60 within the housing 42. At each side of the housing42 are protrusions or knobs 52. As shown, the knobs 52 may have smoothsurfaces to allow smooth articulating movement of the upper platecomponent 20 relative to the base 40. In some embodiments, these knobs52 are rounded and configured with a complementary shape to the grooves28 of the upper plate component 20. The upper plate component 20 may beconfigured to sit over and on top of the housing 42. The upper platecomponent 20 and lower plate component 40 may be tapered at their freeends at the first, leading end 12 of the cage 10, if so desired.

As further shown, the pin 60 may comprise an elongate shaft 64 attachedto which is an enlarged pin head 68. As further shown, the enlarged headportion 68 may include a shoulder 72 or notched portion. In use, the pin60 serves to help tilt, or pivot, the upper plate component 20 relativeto the bottom plate component or base 40, and also blocks the movementof the components 20, 40 once the final configuration has been achieved,so that the position may be locked and no further movement occurs.

As mentioned above, the implantable devices of the present disclosuremay be manufactured in such a way that the processing of all componentsinto the final assembled device is achieved in one step bygenerative/additive production techniques (e.g., selective laser melting(SLM) or other similar techniques as mentioned above). FIGS. 4A and 4Billustrate an exemplary manufacturing configuration showing how the cage10 and the blocking pin 60 can be manufactured nested together undersuch a technique. It should be noted how the benefits ofgenerative/additive production techniques may be utilized here toprovide a multi-component assembly with interactive components that donot require any additional external fixation elements to maintain thesesubcomponents intact and interacting with one another. As can be seen,the entire assembly of cage 10 plus blocking pin 60 may be producedaltogether as one unit having movable internal parts.

As previously mentioned, devices manufactured in this manner would nothave connection seams whereas devices traditionally manufactured wouldhave joined seams to connect one component to another. These connectionseams can often represent weakened areas of the implantable device,particularly when the bonds of these seams wear or break over time withrepeated use or under stress. By manufacturing the disclosed implantabledevices using additive manufacturing, one of the advantages with thesedevices is that connection seams are avoided entirely and therefore theproblem is avoided.

Another advantage of the present devices is that, by manufacturing thesedevices using an additive manufacturing process, all of the componentsof the device (that is, both the intervertebral cage and the pins forexpanding and blocking) remain a complete construct during both theinsertion process as well as the expansion process. That is, multiplecomponents are provided together as a collective single unit so that thecollective single unit is inserted into the patient, actuated to allowexpansion, and then allowed to remain as a collective single unit insitu. In contrast to other cages requiring external expansion screws orwedges for expansion, in the present embodiments the expansion andblocking components do not need to be inserted into the cage, norremoved from the cage, at any stage during the process. This is becausethese components are manufactured to be captured internal to the cages,and while freely movable within the cage, are already contained withinthe cage so that no additional insertion or removal is necessary.

FIGS. 5A to 5C illustrate in greater detail the upper plate component 20of the intervertebral cage 10 of the present disclosure. As shown, theupper plate component 20 may comprise a pair of extended arms orsidewalls 24 between which is a cavity or slot 26 that is configured toreceive the pin 60 as well as cooperate with the housing 42 of the base40. Each of the extended sidewalls 24 may include an undercut surface orgroove 28. The groove 28 may be configured to receive and cooperate withthe knobs 52 of the base 40, and may have a rounded shape in oneembodiment as shown. As illustrated, the upper plate component 20 fitsover and onto the lower base plate component 40, with the extended armsor sidewalls 24 fitting over the housing 42 such that the knobs 52 fitinside the grooves 28 of the sidewalls 24. The inner cavity 26 mayfurther include a bevel surface 34 as well as a blocking surface 36,which features will be described in more detail below.

FIGS. 6A to 6C illustrate in greater detail the lower plate component orbase 40 of the intervertebral cage 10 of the present disclosure. Asshown and as previously discussed, the lower plate component 40 maycomprise a housing 42 and a cavity or slot 48 therein. This cavity 48may be configured to receive the blocking pin 60 and may also includeguiding surfaces 50. On the external surface of either side of thehousing 42 are knobs or protrusions 52. These protrusions 52 may have asmooth, contoured surface that complement or match the grooves 28 of theupper plate component 20 to allow these components to fit together andmove relative to one another, thereby creating an articulating jointbetween the upper and lower plate components 20, 40. The housing 42 mayalso include on its sides a stop ramp 56.

At the rear of the base 40 near the second, trailing end 14 of the cage10 resides the port or channel 44 for receiving the pin shaft 64.Surrounding the channel 44 is the instrument interface 80, which can beseen in an enlarged detailed view in FIG. 6C. The instrument interface80 may be configured to adapt to a bayonet-type connection to allow adelivery instrument, for example, to be attached to the device 10. Theinstrument interface 80 may include an outer contact surface 82, abayonet fitting 84, recesses 86 surrounding the channel 44 forinstrument insertion, and a cylindrical guiding surface 88 provided bythe port or channel 44. Collectively, the instrument interface 80provides the necessary structure for attachment to other instruments,including delivery instruments for inserting the implantable device 10and/or tools for rotating the blocking pin 60.

FIGS. 7A and 7B illustrate the details of the blocking pin 60 that maybe used with the intervertebral cage 10 of the present disclosure. Theblocking pin 60 may comprise an elongate shaft 64 attached to which isan enlarged pin head 68. The pin head 68 may have a guiding surface 70and a shoulder portion 72. The shoulder portion 72 serves as theadjustment surface and may be adjacent to a ridge 74 that serves as abumper or shoulder stop when pressed against the stop ramp 56 of theupper plate component 20.

FIGS. 8A-8J illustrate the process of expanding and angularly adjustingthe intervertebral cage 10 of the present disclosure. In its initialinsertion stage or configuration, the expandable cage 10 may have acompressed, reduced size whereby the upper plate component 20 and lowerplate component 40 are angled towards one another at the first, leadingend 12 of the cage 10 or towards the anterior, as shown in FIGS. 8A and8B. This creates a tapered nose or leading tip, and the slimmest profile(i.e., the smallest anterior height) to facilitate insertion, which isparticularly beneficial to traverse the narrow access path to theimplant site. In some embodiments, the ends of the plate components 20,40 can also include a bevel or taper, if desired. The plate components20, 40 may each include flat external surfaces to contact and pressagainst the endplates of the vertebral bodies.

The blocking pin 60, which may be additively manufactured to residewithin the cage 10 itself in a first insertion configuration, does notinterfere with the pivoting of the plate components 20, 40, and can beconsidered in a non-active state at this point. As shown, the blockingpin 60 rests within the cavity 48 of the housing 42 but does not in thisconfiguration abut the bevel surface 34 or shoulder 52 of the platecomponents 20, 40.

FIGS. 8C and 8D show the cage 10 in an intermediate position orconfiguration. In this configuration, the upper and lower platecomponents 20, 40 are parallel to one another, and defines the smallestinsertion height possible for the intervertebral cage 10. Note that theblocking pin 60 has advanced anteriorly or towards the first, leadingend 12 in this intermediate configuration, and that the enlarged head 68is urging against the upper plate component 20. Once the cage 10 haspassed through the narrow access path and into theintervertebral/intradiscal space, the blocking pin 60 may continue to beadvanced, as shown in FIGS. 8E and 8F. The advancement of the blockingpin 60 anteriorly or towards the first, leading end 12 results in thepivoting of the upper plate component 20 relative to the lower platecomponent 40. The plate components 20, 40 become angled or partiallyopen, with the anterior height being greater than the posterior height,as shown.

FIGS. 8G and 8H show the cage 10 continuing in its active adjustmentphase and load transfer at the posterior of the cage 10. As the blockingpin 60 is advanced anteriorly, the plate components 20, 40 continue tobe angled towards the posterior and increasingly open towards theanterior. As shown in FIGS. 8I and 8J, the cage 10 may now have thegreatest anterior height possible when fully adjusted, which is when theblocking pin 60 is at its anterior-most position within the housing 42and cavities 26, 48 of the upper and lower plate components, 20, 40. Inthis configuration, the load transfer is at the posterior of the cage 10and the cage 10 is fully expanded or adjusted, and in its blocked orlocked position. The shoulder 72 and ridge 74 of the enlarged pin head68 abuts against the beveled surface 34 and blocking surface 36 of theupper plate component 20.

In this final, expanded position, the cage 10 is effective inaccommodating the lordosis angle of the vertebral segment, and canrestore sagittal balance and alignment to the spine. The platecomponents 20, 40 are configured to press against the endplates of thevertebral bodies and can now immobilize and stabilize this region. Asmentioned above, the intervertebral cages of the present disclosure areconfigured to be able to allow insertion through a narrow access path,but are able to be expanded and angularly adjusted so that the cages arecapable of adjusting the angle of lordosis of the vertebral segments. Bybeing able to smoothly pivot at the joint where the knobs 52 articulateinside the grooves 28, the upper plate component 20 may effectivelysee-saw relative to the base or lower plate component 40 to allow a verynarrow anterior for insertion and a larger anterior after implantationto accommodate and adapt to larger angles of lordosis.

As mentioned above, the intervertebral cages of the present disclosureare configured to be able to allow insertion through a narrow accesspath, but are able to be expanded and angularly adjusted so that thecages are capable of adjusting the angle of lordosis of the vertebralsegments. By being able to smoothly roll at the articulating joint, theupper plate component 20 may effectively see-saw relative to the base orlower plate component 40 to allow a very narrow anterior for insertionand a larger anterior after implantation to accommodate and adapt tolarger angles of lordosis. Additionally, the cage can effectivelyrestore sagittal balance and alignment of the spine, and can promotefusion to immobilize and stabilize the spinal segment.

With respect to the ability of the expandable cages 10 to promotefusion, many in-vitro and in-vivo studies on bone healing and fusionhave shown that porosity is necessary to allow vascularization, and thatthe desired infrastructure for promoting new bone growth should have aporous interconnected pore network with surface properties that areoptimized for cell attachment, migration, proliferation anddifferentiation. At the same time, there are many who believe theimplant's ability to provide adequate structural support or mechanicalintegrity for new cellular activity is the main factor to achievingclinical success, while others emphasize the role of porosity as the keyfeature. Regardless of the relative importance of one aspect incomparison to the other, what is clear is that both structural integrityto stabilize, as well as the porous structure to support cellulargrowth, are key components of proper and sustainable bone regrowth.

Accordingly, these cages 10 may take advantage of current additivemanufacturing techniques that allow for greater customization of thedevices by creating a unitary body that may have both solid and porousfeatures in one. In some embodiments, the cages 10 can have a porousstructure, and be made with an engineered cellular structure thatincludes a network of pores, microstructures and nanostructures tofacilitate osteosynthesis. For example, the engineered cellularstructure can comprise an interconnected network of pores and othermicro and nano sized structures that take on a mesh-like appearance.These engineered cellular structures can be provided by etching orblasting to change the surface of the device on the nano level. One typeof etching process may utilize, for example, HF acid treatment. Thesesame manufacturing techniques may be employed to provide these cageswith an internal imaging marker. For example, these cages can alsoinclude internal imaging markers that allow the user to properly alignthe cage and generally facilitate insertion through visualization duringnavigation. The imaging marker shows up as a solid body amongst the meshunder x-ray, fluoroscopy or CT scan, for example. A cage may comprise asingle marker, or a plurality of markers. These internal imaging markersgreatly facilitate the ease and precision of implanting the cages, sinceit is possible to manufacture the cages with one or more internallyembedded markers for improved visualization during navigation andimplantation.

Another benefit provided by the implantable devices of the presentdisclosure is that they are able to be specifically customized to thepatient's needs. Customization of the implantable devices is relevant toproviding a preferred modulus matching between the implant device andthe various qualities and types of bone being treated, such as forexample, cortical versus cancellous, apophyseal versus central, andsclerotic versus osteopenic bone, each of which has its own differentcompression to structural failure data. Likewise, similar data can alsobe generated for various implant designs, such as for example, porousversus solid, trabecular versus non-trabecular, etc. Such data may becadaveric, or computer finite element generated. Clinical correlationwith, for example, DEXA data can also allow implantable devices to bedesigned specifically for use with sclerotic, normal, or osteopenicbone. Thus, the ability to provide customized implantable devices suchas the ones provided herein allow the matching of the Elastic Modulus ofComplex Structures (EMOCS), which enable implantable devices to beengineered to minimize mismatch, mitigate subsidence and optimizehealing, thereby providing better clinical outcomes.

A variety of spinal implants may be provided by the present disclosure,including interbody fusion cages for use in either the cervical orlumbar region of the spine. Although only a posterior lumbar interbodyfusion (PLIF) device is shown, it is contemplated that the sameprinciples may be utilized in a cervical interbody fusion (CIF) device,a transforaminal lumbar interbody fusion (TLIF) device, anterior lumbarinterbody fusion (ALIF) cages, lateral lumbar interbody fusion (LLIF)cages, and oblique lumbar interbody fusion (OLIF) cages.

Other embodiments of the disclosure will be apparent to those skilled inthe art from consideration of the specification and practice of thedisclosure provided herein. It is intended that the specification andexamples be considered as exemplary only.

What is claimed is:
 1. An expandable spinal implant defining a posteriorportion and an anterior portion spaced from the posterior portion in ananterior direction, the expandable spinal implant comprising: an upperplate component configured for placement against an endplate of a firstvertebral body, and a lower plate component configured for placementagainst an endplate of a second, adjacent vertebral body; and a blockingpin comprising an enlarged head portion and a shaft that extends fromthe enlarged head portion in a posterior direction that is opposite theanterior direction, the blocking pin being movable in the anteriordirection from an initial position to an anterior-most position, whereineach of the upper and lower plate components defines a respective pairof side walls that are spaced from each other along a direction that isperpendicular to the anterior direction so as to define a cavitytherebetween, and the respective pair of side walls of one of the upperand lower plate components is disposed in the cavity of the other of theupper and lower plate components, such that respective projections onone of the pair of side walls fit into respective grooves in the otherpair of side walls so as to define an articulating joint of the upperand lower plate components, and wherein when the blocking pin is in theinitial position, the implant is in a first configuration whereby theplate components are angled toward each other from the posterior portionto the anterior portion, and when the blocking pin moves in the anteriordirection to the anterior-most position, the enlarged head portion bearsagainst the upper and lower plate components, thereby urging the implantto articulate about the articulating joint to a second configurationwhereby the plate components are angled toward each other at theposterior portion as they extend in a posterior direction that isopposite the anterior direction.
 2. The expandable spinal implant ofclaim 1, wherein the spinal implant including the blocking pin ismanufactured by one of a selective laser melting (SLM) technique, 3Dprinting, electron beam melting (EBM), and layer deposition.
 3. Theexpandable spinal implant of claim 2, wherein the implant does not haveany connection seams.
 4. The expandable spinal implant of claim 1,wherein the blocking pin is manufactured to reside inside the respectivecavities of the upper and lower plate components of the expandablespinal implant.
 5. The expandable spinal implant of claim 1, wherein theupper plate component defines the grooves that extend into respectiveinterior surfaces of the respective side walls of the upper platecomponent, and the lower plate component comprises the projections thatextend from exterior surfaces of the respective side walls of the lowerplate component.
 6. The expandable spinal implant of claim 1, whereinthe upper and lower plate components pivot about the articulating jointallows pivoting movement of the upper and lower plate componentsrelative to one another as the blocking pin is moved in the anteriordirection to the anterior-most position.
 7. The expandable spinalimplant of claim 1, wherein either of the upper plate component or lowerbase components includes a flat surface for placement against theendplate of either of the first or second, adjacent vertebral bodies. 8.The expandable spinal implant of claim 1, wherein the blocking pin locksthe upper and lower plate components together at its anterior-mostposition.
 9. The expandable spinal implant of claim 1, wherein the upperand lower plate components are tapered at one of their free ends. 10.The expandable spinal implant of claim 1, further being configured as aPLIF cage.
 11. The expendable spinal implant of claim 1, wherein theupper and lower plate components define a porous structure.
 12. Theexpandable spinal implant of claim 11, wherein the porous structurecomprises an engineered cellular structure.
 13. The expandable spinalimplant of claim 11, wherein the porous structure comprises a mesh-likestructure.
 14. The expandable spinal implant of claim 1, furtherincluding an internal imaging marker.
 15. The expandable spinal implantof claim 1, having an intermediate configuration when the blocking pinis between the initial configuration and the anterior-most position,whereby the plate components are generally parallel to one another. 16.The expandable spinal implant of claim 1, wherein the plate componentsare locked together when the blocking pin is in the anterior-mostposition.
 17. The expandable spinal implant of claim 1, wherein when theblocking pin is in the anterior-most position, the plate components areangled away from each other at the anterior portion of the spinalimplant as they extend in the anterior direction.
 18. The expandablespinal implant of claim 1, wherein the upper plate component and thelower plate component cooperate to capture the enlarged head portionbetween the anterior portion and the posterior portion when the blockingpin is in the initial position.
 19. The expandable spinal implant ofclaim 18, wherein the enlarged head portion is further captured betweenthe anterior portion and the posterior portion both when the blockingpin is in the anterior-most position, and as the blocking pin isadvanced from the initial configuration to the anterior-most position.20. The expandable spinal implant of claim 1, wherein the platecomponents combine to define the anterior portion of the spinal implantwhen the blocking pin is in the initial configuration.
 21. Theexpandable spinal implant of claim 1, wherein the blocking pin isdisposed in the cavity that is defined by the respective pair of sidewalls of the one of the upper and lower plate components that isdisposed in the cavity of the other of the upper and lower platecomponents.
 22. The expandable spinal implant of claim 1 wherein theblocking pin extends across a midplane of the implant with respect to adirection that includes the anterior and posterior directions both whenthe blocking pin is in the initial position and when the blocking pin isin the anterior-most position.